Personality goes a long way…toward making you sick

This is dangerously close to “day job” territory, but yesterday evening I was on the wireless talking about the relationship between psychological traits and physical health. This was part of the excellent Futureproof show on Newstalk 106-108 fm, hosted by the also-excellent Jonathan McCrea (and produced by the just-as-excellent Shaun O’Boyle). You can access the podcast of the show by clicking here (readers who have sold their souls to iTunes can do their business here). My segment begins at 8:32 and lasts for around twelve minutes.

From a science communication perspective, the item is helpful in addressing a topic that is very often discussed in terms of — how shall I put it? — mumbo jumbo and pseudoscience. For centuries, it has been claimed that personal temperaments affect illness and well-being (consider Galen’s four humours or astrology). Moreover, therapy-merchants of various degrees of rigour have made a good living from offering attractive think-yourself-better solutions for physical health problems.

However, the existence of these psychosomatic superstitions should not take away from the very well empirically supported understanding of how mental states interact with physical disease processes. Functions like bloodpressure regulation are extremely stress-sensitive, and it is relatively easy to show in research studies that chronic stress leads to down-regulation of the immune system. Lots of studies, for example, have shown such down-regulation of immunity among people who carry chronically stressful caregiving responsibilities, such as caring for a loved one with a disability or dementia. Other studies show that people who live with chronic stress also show accelerated biological aging, as demonstrated by the contents of their DNA.

What’s particularly interesting is that we also now know that individuals differ in the degree to which stress influences the processes of illness onset, progression, and recovery inside their bodies. Some people are just naturally more robust against disease risk, even when facing chronic stress. This is partly because of their physical attributes, but also because of their characteristic psychological responses to stressful experiences. In short, some people have more of a tendency than others of becoming extremely anxious, and this can be bad for their biological homeostasis.

Finally, one intriguing element to all this is that most of the personality characteristics that human culture considers to be “psychological” actually turn out to be quite physical, when considered with that possibility in mind. For example, whether a person is “emotional” or “stable” is largely a matter of whether they they are physically arousable or physically stable. The more characteristically ’emotional’ you are, the more likely it is that you respond to excitement with physical reactions like increased blood pressure, heart rate, breathing speed, and blushing, as well as that feeling of nervousness in the pit of your stomach. That is the physical reaction that your body undergoes on the inside — the outwardly obvious elements of that (excitedness, fast talking, hesitation, and upset) is what culture then calls your “personality”. Similar cases can be made for other major personality traits, such as extraversion and conviviality.

Testing a pig's personality. Seriously

And so, that’s why in the interview I end up talking about research looking at personality and well-being in…pigs. Yes, pigs. Have a listen and you’ll see where I’m coming from.

Like a lot of areas, the empirical science here is very far removed from the popular concepts discussed by gurus and pseudotherapists who wish to save your life (in exchange for cash). Promoting scientific literacy is a difficult enterprise, all the more so nowadays when there is so much anti-science around. That’s why radio shows like Futureproof are so important.